CO在NiO（100）面上吸附的近边X射线吸收精细结构理论分析

摘要

用多重散射团簇（MSC）理论对CO在NiO（100）面吸附的碳1s近边X射线吸收精细结构（NEXAFS）实验谱进行了定量分析，研究了该系统可能出现的吸附模型。MSC方法分析表明CO是以C原子朝下，吸附在衬底的Ni-O键桥上，R-factor(可靠性因子）计算显示C原子的吸附位置距Ni原子0.09nm,CO分子中C原子距衬底的吸附高度为0.31±0.01nm。本文讨论了在NiO表面吸附的CO分子σ键的物理本质。与CO在过渡金属Ni,Cu等表面吸附不同，σ共振对于CO键长的依赖不明显。%The carbon 1s near-edge X-ray absorption fine structure(NEXAFS) of CO/NiO(100) system was investigated by the multiple-scattering cluster (MSC) method. The possible theoretical models of adsorption were suggested. The theoretical analysis of NEXAFS shows that CO is perpendicular to the NiO (100) surface. This paper proposed that the CO molecule is taken an asymmetric site adsorbed on Ni-O bridge with 0.09 nm off the top of Ni atom for the first time. R-facter calculations give the results that the adsorption height is equal to 0.31±0.01nm. The physical origin of σ bond of CO/NiO(100) system was discussed, the σ bond does not depend on the C-O bond length. It is quite different from CO adsorbed on metal surfaces.